Blends of polypropylene (PP) and more polar polymers (e.g., nylon) are typically prepared using a compatibilizer such as a maleic anhydride (MA)-grafted PP. Conventionally, functionalization of PP with MA is achieved via melt processing. However, such melt processing techniques are accompanied by drastic reduction in PP molecular weight. Such molecular weight reduction results in detrimental material property change, by comparison to that of the neat PP from which the functionalized PP was made. The molecular weight reduction of PP associated with melt processing is caused by a free-radical chemistry (i.e., β-scission) that is highly dependent on temperature. (See, FIG. 1.) As processing temperature increases, the rate of β-scission increases dramatically. (See, Rätzsch, M.; Arnold, M.; Borsig, E.; Bucka, H.; Reichelt, N. Progress in Polymer Science 2002, 27, 1195-1282 and Dickens, B. Journal of Polymer Science: Polymer Chemistry Edition 1982, 20, 1169-1183.) Because melt processing is carried out at high temperatures (i.e., ˜190-220° C.), the extent of β-scission is typically significant. As a result, there remains an on-going concern in the art to develop an efficient and effective process for the preparation of MA-grafted PP as well as other functionalized polyolefins. This need, as well as its expected impact on the properties of the resulting polymeric materials, has been recognized and illustrated clearly in literature: The incorporation of functional groups along the backbone of polyolefins such as polyethylene and polypropylene in a selective, controlled, and mild manner is considered to be one of the most important challenges currently facing synthetic polymer chemists. (See, Boaen, N. K.; Hillmyer, M. A. Chemical Society Reviews 2005, 34, 267-75).